An increase in the number of flights arriving in and departing from Greece is putting local air-traffic controllers under too much stress, their union said on Wednesday as it announced plans to launch protest action next month.

The union said that its members’ health and air safety are at risk and called for more funding for training, wages and equipment to be made available.

It said that over the weekend an air-traffic controller felt pains in his chest while he was on duty and had to be taken to the hospital. The union said that this incident was indicative of the pressure created by the record number of flights in Greek air space this summer.